/Engine/Source/Runtime/MeshConversion/Public/DynamicMeshToMeshDescription.h
Checks if element counts match. If false then Update can't be called  you must call Convert
static bool HaveMatchingElementCounts ( const [FDynamicMesh3](API\Runtime\GeometryCore\DynamicMesh\FDynamicMesh3) * DynamicMesh, const [FMeshDescription](API\Runtime\MeshDescription\FMeshDescription) * MeshDescription, bool bVerticesOnly, bool bAttributesOnly )